Kinetics of silicon refining using slag treatment

Silicon, an important semiconducting material and alloying element in metallurgy and chemistry, is one the most abundant elements in the earth as oxides and silicates. The rapid growth of solar cell demand is creating a shortage of solar-grade silicon feedstock. Expensive high-purity scrap silicon (99.9999999% Si) is mainly used as the raw material to produce solar-grade silicon (SOG-Si) (99.9999% Si). Many researchers have reported that relatively inexpensive metallurgical grade silicon (MG-Si) (98-99% Si) can be used as an alternative raw material. Of all the impurities present in MG-Si, boron and phosphorus are usually the most difficult to remove. Slag refining is one of the few metallurgical methods for the efficient removal of boron from silicon. In order to produce silicon for photovoltaic applications, the relationship between the slag composition and the mass transfer rate of boron from silicon to slag is of great importance.